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Message-Id: <20120717.085803.1895534004244751687.davem@davemloft.net>
Date: Tue, 17 Jul 2012 08:58:03 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: netdev@...r.kernel.org
CC: eric.dumazet@...il.com
Subject: [PATCH 5/5 v2] ipv4: Add FIB nexthop exceptions.
In a regime where we have subnetted route entries, we need a way to
store persistent storage about destination specific learned values
such as redirects and PMTU values.
This is implemented here via nexthop exceptions.
The initial implementation is a 2048 entry hash table with relaiming
starting at chain length 5. A more sophisticated scheme can be
devised if that proves necessary.
Signed-off-by: David S. Miller <davem@...emloft.net>
---
Eric, just for you :-)
include/net/ip_fib.h | 18 ++++
net/ipv4/fib_semantics.c | 23 +++++
net/ipv4/route.c | 256 ++++++++++++++++++++++++++++++++++++++++------
3 files changed, 266 insertions(+), 31 deletions(-)
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 5697ace..e9ee1ca 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -18,6 +18,7 @@
#include <net/flow.h>
#include <linux/seq_file.h>
+#include <linux/rcupdate.h>
#include <net/fib_rules.h>
#include <net/inetpeer.h>
@@ -46,6 +47,22 @@ struct fib_config {
struct fib_info;
+struct fib_nh_exception {
+ struct fib_nh_exception __rcu *fnhe_next;
+ __be32 fnhe_daddr;
+ u32 fnhe_pmtu;
+ u32 fnhe_gw;
+ unsigned long fnhe_expires;
+ unsigned long fnhe_stamp;
+};
+
+struct fnhe_hash_bucket {
+ struct fib_nh_exception __rcu *chain;
+};
+
+#define FNHE_HASH_SIZE 2048
+#define FNHE_RECLAIM_DEPTH 5
+
struct fib_nh {
struct net_device *nh_dev;
struct hlist_node nh_hash;
@@ -63,6 +80,7 @@ struct fib_nh {
__be32 nh_gw;
__be32 nh_saddr;
int nh_saddr_genid;
+ struct fnhe_hash_bucket *nh_exceptions;
};
/*
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index d71bfbd..1e09852 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -140,6 +140,27 @@ const struct fib_prop fib_props[RTN_MAX + 1] = {
},
};
+static void free_nh_exceptions(struct fib_nh *nh)
+{
+ struct fnhe_hash_bucket *hash = nh->nh_exceptions;
+ int i;
+
+ for (i = 0; i < FNHE_HASH_SIZE; i++) {
+ struct fib_nh_exception *fnhe;
+
+ fnhe = rcu_dereference(hash[i].chain);
+ while (fnhe) {
+ struct fib_nh_exception *next;
+
+ next = rcu_dereference(fnhe->fnhe_next);
+ kfree(fnhe);
+
+ fnhe = next;
+ }
+ }
+ kfree(hash);
+}
+
/* Release a nexthop info record */
static void free_fib_info_rcu(struct rcu_head *head)
{
@@ -148,6 +169,8 @@ static void free_fib_info_rcu(struct rcu_head *head)
change_nexthops(fi) {
if (nexthop_nh->nh_dev)
dev_put(nexthop_nh->nh_dev);
+ if (nexthop_nh->nh_exceptions)
+ free_nh_exceptions(nexthop_nh);
} endfor_nexthops(fi);
release_net(fi->fib_net);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index b35d3bf..a5bd0b4 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1275,14 +1275,130 @@ static void rt_del(unsigned int hash, struct rtable *rt)
spin_unlock_bh(rt_hash_lock_addr(hash));
}
-static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
+static void __build_flow_key(struct flowi4 *fl4, struct sock *sk,
+ const struct iphdr *iph,
+ int oif, u8 tos,
+ u8 prot, u32 mark, int flow_flags)
+{
+ if (sk) {
+ const struct inet_sock *inet = inet_sk(sk);
+
+ oif = sk->sk_bound_dev_if;
+ mark = sk->sk_mark;
+ tos = RT_CONN_FLAGS(sk);
+ prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
+ }
+ flowi4_init_output(fl4, oif, mark, tos,
+ RT_SCOPE_UNIVERSE, prot,
+ flow_flags,
+ iph->daddr, iph->saddr, 0, 0);
+}
+
+static void build_skb_flow_key(struct flowi4 *fl4, struct sk_buff *skb, struct sock *sk)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ int oif = skb->dev->ifindex;
+ u8 tos = RT_TOS(iph->tos);
+ u8 prot = iph->protocol;
+ u32 mark = skb->mark;
+
+ __build_flow_key(fl4, sk, iph, oif, tos, prot, mark, 0);
+}
+
+static void build_sk_flow_key(struct flowi4 *fl4, struct sock *sk)
+{
+ const struct inet_sock *inet = inet_sk(sk);
+ struct ip_options_rcu *inet_opt;
+ __be32 daddr = inet->inet_daddr;
+
+ rcu_read_lock();
+ inet_opt = rcu_dereference(inet->inet_opt);
+ if (inet_opt && inet_opt->opt.srr)
+ daddr = inet_opt->opt.faddr;
+ flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
+ RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
+ inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
+ inet_sk_flowi_flags(sk),
+ daddr, inet->inet_saddr, 0, 0);
+ rcu_read_unlock();
+}
+
+static void ip_rt_build_flow_key(struct flowi4 *fl4, struct sock *sk,
+ struct sk_buff *skb)
+{
+ if (skb)
+ build_skb_flow_key(fl4, skb, sk);
+ else
+ build_sk_flow_key(fl4, sk);
+}
+
+static DEFINE_SPINLOCK(fnhe_lock);
+
+static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash, __be32 daddr)
+{
+ struct fib_nh_exception *fnhe, *oldest;
+
+ oldest = rcu_dereference(hash->chain);
+ for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
+ fnhe = rcu_dereference(fnhe->fnhe_next)) {
+ if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
+ oldest = fnhe;
+ }
+ return oldest;
+}
+
+static struct fib_nh_exception *find_or_create_fnhe(struct fib_nh *nh, __be32 daddr)
+{
+ struct fnhe_hash_bucket *hash = nh->nh_exceptions;
+ struct fib_nh_exception *fnhe;
+ int depth;
+ u32 hval;
+
+ if (!hash) {
+ hash = nh->nh_exceptions = kzalloc(FNHE_HASH_SIZE * sizeof(*hash),
+ GFP_ATOMIC);
+ if (!hash)
+ return NULL;
+ }
+
+ hval = (__force u32) daddr;
+ hval ^= (hval >> 11) ^ (hval >> 22);
+ hash += hval;
+
+ depth = 0;
+ for (fnhe = rcu_dereference(hash->chain); fnhe;
+ fnhe = rcu_dereference(fnhe->fnhe_next)) {
+ if (fnhe->fnhe_daddr == daddr)
+ goto out;
+ depth++;
+ }
+
+ if (depth > FNHE_RECLAIM_DEPTH) {
+ fnhe = fnhe_oldest(hash + hval, daddr);
+ goto out_daddr;
+ }
+ fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
+ if (!fnhe)
+ return NULL;
+
+ fnhe->fnhe_next = hash->chain;
+ rcu_assign_pointer(hash->chain, fnhe);
+
+out_daddr:
+ fnhe->fnhe_daddr = daddr;
+out:
+ fnhe->fnhe_stamp = jiffies;
+ return fnhe;
+}
+
+static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4)
{
__be32 new_gw = icmp_hdr(skb)->un.gateway;
__be32 old_gw = ip_hdr(skb)->saddr;
struct net_device *dev = skb->dev;
struct in_device *in_dev;
+ struct fib_result res;
struct neighbour *n;
- struct rtable *rt;
struct net *net;
switch (icmp_hdr(skb)->code & 7) {
@@ -1296,7 +1412,6 @@ static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buf
return;
}
- rt = (struct rtable *) dst;
if (rt->rt_gateway != old_gw)
return;
@@ -1320,11 +1435,21 @@ static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buf
goto reject_redirect;
}
- n = ipv4_neigh_lookup(dst, NULL, &new_gw);
+ n = ipv4_neigh_lookup(&rt->dst, NULL, &new_gw);
if (n) {
if (!(n->nud_state & NUD_VALID)) {
neigh_event_send(n, NULL);
} else {
+ if (fib_lookup(net, fl4, &res) == 0) {
+ struct fib_nh *nh = &FIB_RES_NH(res);
+ struct fib_nh_exception *fnhe;
+
+ spin_lock_bh(&fnhe_lock);
+ fnhe = find_or_create_fnhe(nh, fl4->daddr);
+ if (fnhe)
+ fnhe->fnhe_gw = new_gw;
+ spin_unlock_bh(&fnhe_lock);
+ }
rt->rt_gateway = new_gw;
rt->rt_flags |= RTCF_REDIRECTED;
call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
@@ -1349,6 +1474,17 @@ reject_redirect:
;
}
+static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
+{
+ struct rtable *rt;
+ struct flowi4 fl4;
+
+ rt = (struct rtable *) dst;
+
+ ip_rt_build_flow_key(&fl4, sk, skb);
+ __ip_do_redirect(rt, skb, &fl4);
+}
+
static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
{
struct rtable *rt = (struct rtable *)dst;
@@ -1508,33 +1644,51 @@ out: kfree_skb(skb);
return 0;
}
-static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
- struct sk_buff *skb, u32 mtu)
+static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
{
- struct rtable *rt = (struct rtable *) dst;
-
- dst_confirm(dst);
+ struct fib_result res;
if (mtu < ip_rt_min_pmtu)
mtu = ip_rt_min_pmtu;
+ if (fib_lookup(dev_net(rt->dst.dev), fl4, &res) == 0) {
+ struct fib_nh *nh = &FIB_RES_NH(res);
+ struct fib_nh_exception *fnhe;
+
+ spin_lock_bh(&fnhe_lock);
+ fnhe = find_or_create_fnhe(nh, fl4->daddr);
+ if (fnhe) {
+ fnhe->fnhe_pmtu = mtu;
+ fnhe->fnhe_expires = jiffies + ip_rt_mtu_expires;
+ }
+ spin_unlock_bh(&fnhe_lock);
+ }
rt->rt_pmtu = mtu;
dst_set_expires(&rt->dst, ip_rt_mtu_expires);
}
+static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
+ struct sk_buff *skb, u32 mtu)
+{
+ struct rtable *rt = (struct rtable *) dst;
+ struct flowi4 fl4;
+
+ ip_rt_build_flow_key(&fl4, sk, skb);
+ __ip_rt_update_pmtu(rt, &fl4, mtu);
+}
+
void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
int oif, u32 mark, u8 protocol, int flow_flags)
{
- const struct iphdr *iph = (const struct iphdr *)skb->data;
+ const struct iphdr *iph = (const struct iphdr *) skb->data;
struct flowi4 fl4;
struct rtable *rt;
- flowi4_init_output(&fl4, oif, mark, RT_TOS(iph->tos), RT_SCOPE_UNIVERSE,
- protocol, flow_flags,
- iph->daddr, iph->saddr, 0, 0);
+ __build_flow_key(&fl4, NULL, iph, oif,
+ RT_TOS(iph->tos), protocol, mark, flow_flags);
rt = __ip_route_output_key(net, &fl4);
if (!IS_ERR(rt)) {
- ip_rt_update_pmtu(&rt->dst, NULL, skb, mtu);
+ __ip_rt_update_pmtu(rt, &fl4, mtu);
ip_rt_put(rt);
}
}
@@ -1542,27 +1696,31 @@ EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
{
- const struct inet_sock *inet = inet_sk(sk);
+ const struct iphdr *iph = (const struct iphdr *) skb->data;
+ struct flowi4 fl4;
+ struct rtable *rt;
- return ipv4_update_pmtu(skb, sock_net(sk), mtu,
- sk->sk_bound_dev_if, sk->sk_mark,
- inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
- inet_sk_flowi_flags(sk));
+ __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
+ rt = __ip_route_output_key(sock_net(sk), &fl4);
+ if (!IS_ERR(rt)) {
+ __ip_rt_update_pmtu(rt, &fl4, mtu);
+ ip_rt_put(rt);
+ }
}
EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
void ipv4_redirect(struct sk_buff *skb, struct net *net,
int oif, u32 mark, u8 protocol, int flow_flags)
{
- const struct iphdr *iph = (const struct iphdr *)skb->data;
+ const struct iphdr *iph = (const struct iphdr *) skb->data;
struct flowi4 fl4;
struct rtable *rt;
- flowi4_init_output(&fl4, oif, mark, RT_TOS(iph->tos), RT_SCOPE_UNIVERSE,
- protocol, flow_flags, iph->daddr, iph->saddr, 0, 0);
+ __build_flow_key(&fl4, NULL, iph, oif,
+ RT_TOS(iph->tos), protocol, mark, flow_flags);
rt = __ip_route_output_key(net, &fl4);
if (!IS_ERR(rt)) {
- ip_do_redirect(&rt->dst, NULL, skb);
+ __ip_do_redirect(rt, skb, &fl4);
ip_rt_put(rt);
}
}
@@ -1570,12 +1728,16 @@ EXPORT_SYMBOL_GPL(ipv4_redirect);
void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
{
- const struct inet_sock *inet = inet_sk(sk);
+ const struct iphdr *iph = (const struct iphdr *) skb->data;
+ struct flowi4 fl4;
+ struct rtable *rt;
- return ipv4_redirect(skb, sock_net(sk), sk->sk_bound_dev_if,
- sk->sk_mark,
- inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
- inet_sk_flowi_flags(sk));
+ __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
+ rt = __ip_route_output_key(sock_net(sk), &fl4);
+ if (!IS_ERR(rt)) {
+ __ip_do_redirect(rt, skb, &fl4);
+ ip_rt_put(rt);
+ }
}
EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
@@ -1722,14 +1884,46 @@ static void rt_init_metrics(struct rtable *rt, const struct flowi4 *fl4,
dst_init_metrics(&rt->dst, fi->fib_metrics, true);
}
+static void rt_bind_exception(struct rtable *rt, struct fib_nh *nh, __be32 daddr)
+{
+ struct fnhe_hash_bucket *hash = nh->nh_exceptions;
+ struct fib_nh_exception *fnhe;
+ u32 hval;
+
+ hval = (__force u32) daddr;
+ hval ^= (hval >> 11) ^ (hval >> 22);
+
+ for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
+ fnhe = rcu_dereference(fnhe->fnhe_next)) {
+ if (fnhe->fnhe_daddr == daddr) {
+ if (fnhe->fnhe_pmtu) {
+ unsigned long expires = fnhe->fnhe_expires;
+ unsigned long diff = jiffies - expires;
+
+ if (time_before(jiffies, expires)) {
+ rt->rt_pmtu = fnhe->fnhe_pmtu;
+ dst_set_expires(&rt->dst, diff);
+ }
+ }
+ if (fnhe->fnhe_gw)
+ rt->rt_gateway = fnhe->fnhe_gw;
+ fnhe->fnhe_stamp = jiffies;
+ break;
+ }
+ }
+}
+
static void rt_set_nexthop(struct rtable *rt, const struct flowi4 *fl4,
const struct fib_result *res,
struct fib_info *fi, u16 type, u32 itag)
{
if (fi) {
- if (FIB_RES_GW(*res) &&
- FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK)
- rt->rt_gateway = FIB_RES_GW(*res);
+ struct fib_nh *nh = &FIB_RES_NH(*res);
+
+ if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK)
+ rt->rt_gateway = nh->nh_gw;
+ if (unlikely(nh->nh_exceptions))
+ rt_bind_exception(rt, nh, fl4->daddr);
rt_init_metrics(rt, fl4, fi);
#ifdef CONFIG_IP_ROUTE_CLASSID
rt->dst.tclassid = FIB_RES_NH(*res).nh_tclassid;
--
1.7.10.4
--
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